Optical code scanners are used in a wide variety of applications that rely on information stored in optical codes. Industries such as retail, airline, self-service, automotive, parcel delivery, pharmaceutical, healthcare and others use optical codes to provide inventory control, customer identification, product identification, item tracking, security and many other functions. Bar codes are a type of optical code in wide use and a bar code scanner is a type of optical code scanner used to read bar codes. A typical bar code is comprised of a number of bars separated by spaces. Information is encoded in a bar code by varying the width of the bars and spaces. When a bar code is placed within the field of view of a bar code scanner, the scanner will detect, analyze and decode the bars and spaces comprising the bar code to retrieve the information encoded wherein. This operation is also called scanning or reading a bar code. The information encoded on a bar code is usually a sequence of numeric or alphanumeric symbols (e.g., a Universal Product Code (UPC) or European Article Number (EAN)).
An imaging bar code scanner (also referred to as an image scanner) reads a bar code by capturing a digital image of the bar code and then processing the image to detect and decode the bar code. It is advantageous for the bar code scanner to successfully read all bar codes presented to the scanner on the first pass of each bar code by the scanner. This is known as a successful first pass read. Successful first pass reads of bar codes helps to maintain a good workflow at the checkout station and speeds up the overall checkout process. A high success rate for first pass reads has also been found to reduce stress on the person operating the scanner. This is particularly true if the operator is a customer operating a self-checkout terminal.
High performance passby barcode scanners based upon image capture and image processing technology have been slow to be adopted in passby scanning environments. In a retail environment, an image scanner must achieve high read success rates with object passby speeds of 30 to 50 inches per second. The image scanners on the market today have not proved capable of such speeds, which is one reason why laser based barcode scanners dominate the passby scanning environments.
One important barrier that has prevented image scanners from reaching high passby speeds is related to the detection of a bar code that is not aligned with the pixel rows of an image capture device used to capture an image of the bar code. A non-aligned or angled bar code is more difficult to detect because no single row of pixel data contains sufficient information to detect and decode the bar code. Therefore, multiple rows of pixel data must be read and analyzed before the bar code can be detected and decoded. In addition, lighting conditions may cause the captured image of the optical code to have a low contrast. The combined conditions of bar code non-alignment and low contrast make it very difficult to detect and decode a bar code.
Therefore, it would be desirable to provide an image capture device that over comes these and other problems.